Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 241727

Area Forecast Discussion
National Weather Service Riverton WY
1127 AM MDT Mon Oct 24 2016

.SHORT TERM...Monday through Wednesday night

Things continue to be quiet across the area at this time. Radar does
show a couple of showers across Utah but as expected these are
taking their sweet time in moving into the area. The initial shot of
warm advection / isentropic lift will move into the west during the
morning with a shot of precipitation this morning and less so in the
afternoon. The models continue to struggle with the placement of the
showers, so we kept things fairly generic and made few changes to
continuity. One change we did make was to remove showers East of the
Divide as downsloping flow would likely dry things out for most
areas. As for precipiation type, with the southwest flow 700
millibar temperatures are fairly warm, only falling to around +1
which would put snow levels around 9000 to 9500 feet during the day.
Another shot of steadier precipitation with some jet energy will
move in tonight across the west but even now snow levels should
remain above 8000 feet or so unless the rate of precipitation
becomes very heavy. As for accumulations, there could be several
inches but at this time they look to fall below advisory levels
except for the highest elevations well above pass level where
impacts would be minimal, especially during the day. The day shift
can take a second look to see if anything is needed for tonight.
Both the NAM and GFS are showing another area of decent showers
across eastern Sweetwater County with a jet streak so we increased
POPS and QPF a bit in that location. Meanwhile, East of the Divide
things should remain mild and mainly dry although with a good deal
of mid to high level clouds today. We can`t completely rule out a
shower in a few areas but the chance is so low we left it out for
now. There will also be a gusty breeze at times across the
southwestern Wind Corridor from Rock Springs to Casper with the
tightening pressure gradient.

On Tuesday another shortwave will move across the region from west
to east. This one has some slightly cooler air with it and could
bring snow levels a bit lower. However, it does not have much
moisture to work with so any accumulation would not be much. This
system may have a better chance of producing a shower East of the
Divide as it passes but not much. We did allow for some POPS across
the Bighorn Range however. Temperatures will once again be well
above normal east of the divide and near normal in the west.

Precipiation should end by later Tuesday night as ridging builds
back into the area. Wednesday at this point looks to be a dry and
mild day for all areas. A shortwave moving across Montana could
bring some locally gusty wind to portions of the northern mountains
but any precipitation should remain well north of Wyoming.

.LONG TERM...Thursday Through Monday

Models struggling mightily with the mean trough/split flow pattern
that remains generally off the West Coast through the period.
Leaned somewhat towards the GFS/GEM which at least have some
similarities with multiple shortwaves that rotate out of the
trough and move ne across across the west/north at times. First
one probably brushes the far n/nw on Thursday with nothing more
than some nrn mtn flurries/sprinkles at best. Otherwise, a mild
late October day with some clouds/lee enhancement to worry about
as the ridge axis is just east of us. Next newd moving shortwave
may impact the west around Friday night with some showers/hyr
elevation snow showers. ECMWF shows this one also. Could be strong
enough for a few inches of higher elevation snow in the nw but
it`s rather mild with h7 temps fcst to stay above zero so mostly
lgt rain showers in the lower elevations or mixed at best early in
the morning. System moves quickly off to the east later Saturday
with a dry period into early Sunday. Next potentially stronger
system may arrive later Sunday/Sunday night with somewhat cooler
air and a better chance of mtn snow and possible a mixture in the
lower elevations of the west. Will see how this system looks again
tonight before we start hitting it any harder. Mild still east of
the divide with clouds but h7 temps fcst to be in the +6 to +8
range. Cooler east of the divide behind this system with the GFS
at least showing the north near 0c and the south around +2c after
+8 on Sunday. On last system may begin to approach right at the
end of the medium range period from the southwest. Euro doesn`t
show it and the GEM is slower. Just some slgt chances in the west
for now with this potential system. With the mean trough sitting
near or just off the West Coast, we`ll be susceptible to newd
moving disturbances through the period, maybe a little more
towards the last couple days as the trough may consolidate more
and be slightly further ewd overall.




Moisture will continue to increase over the area this afternoon,
with showers anticipated. A few thunderstorms may also occur,
though look unfavorable to impact any area terminals. With the
ongoing potential for periods of shower activity, mountain tops
will see related obscurations, and periods of MVFR conditions may
be possible, especially at KJAC and KPNA. As the system continues,
models indicate the potential for LLWS over KPNA through the early
afternoon hours, with the threat easing after 21z this afternoon.
Precipitation looks to be rain over below 9500 ft AGL, with
snowfall anticipated above these levels.


Southwest flow will bring a favored scenario for periods of gusty
wind over KCPR this afternoon. Generally dry conditions are
anticipated, though showers over the nearby mountains may send
some rogue activity over KLND and KCOD this afternoon. There is an
indication of the presence of LLWS impacting KLND, which will
remain a threat through around 21z this afternoon. Otherwise, with
mountain showers anticipated to continue under increased
moisture...expect mountain top obscurations through much of the
TAF period.



Fire concerns should remain low today. Moisture moving in from the
south and west will spread clouds across much of the area. A gusty
wind will develop across the southwestern Wind Corridor but
humidity will remain above critical levels. Rain and higher
elevation snow will fall at times West of the Divide today.
Mixing and smoke dispersal will be fair to poor across the most of
the areas but good where gusty southwest winds develop.




SHORT TERM...Hattings
LONG TERM...Skrbac
FIRE WEATHER...Hattings is the U.S. government's official web portal to all federal, state and local government web resources and services.